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Schottky barrier diodes are specialized semiconductor devices characterized by their unique construction. This construction involves combining a metal layer with a moderately doped n-type semiconductor material. This combination leads to the formation of a Schottky barrier, a pivotal element that defines the diode's operational characteristics. The core functionality of Schottky barrier diodes is their capacity to allow current to flow in only one direction due to their distinctive...
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Fabrication of Schottky Diodes on Zn-polar BeMgZnO/ZnO Heterostructure Grown by Plasma-assisted Molecular Beam Epitaxy
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'Collapsing rings' on Schottky electron emitters.

M S Bronsgeest1, P Kruit

  • 1Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands. m.s.bronsgeest@tudelft.nl

Ultramicroscopy
|July 8, 2010
PubMed
Summary
This summary is machine-generated.

Schottky emitter beam instabilities, known as 'collapsing rings', are caused by repetitive tip geometry changes. Monitoring tip current can predict and prevent these fluctuations for stable electron beams.

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Area of Science:

  • Materials Science
  • Electron Optics
  • Surface Physics

Background:

  • Schottky emitters are crucial electron sources in various systems.
  • Periodic beam fluctuations, termed 'collapsing rings', occur at low extraction fields.
  • Previous understanding of 'collapsing rings' lacked detailed insight into underlying mechanisms.

Purpose of the Study:

  • To investigate the detailed tip geometry changes during Schottky emitter beam instabilities.
  • To understand the repetitive process leading to 'collapsing rings'.
  • To identify early detection methods for preventing beam instabilities.

Main Methods:

  • Recorded emission pattern evolution of Schottky emitters exhibiting 'collapsing rings'.
  • Analyzed tip end geometry changes under various operating conditions.
  • Utilized Scanning Electron Microscope (SEM) images to support interpretation.

Main Results:

  • Beam instabilities are linked to a continuous, repetitive cycle of tip end geometry modification.
  • This cycle involves facet size reduction, formation of ring-shaped steps, and island development.
  • Fluctuations correlate with island edges near the electron delivery area; geometry changes affect beam properties.

Conclusions:

  • Schottky emitter tip geometry dynamically changes, leading to beam instabilities.
  • Early detection of facet size reduction via tip current or field enhancement factor can prevent instabilities.
  • Proactive monitoring allows for prevention, unlike reactive voltage adjustments.